Manufacture of spiral wound members



W. W. M MINN ET AL MANUFACTURE OF SPIRAL WOUND MEMBERS Filed May 1942 Patented June 12, 1945 ou srmen womo 'MEMBER'S Wiley w. McMinn; orange, and one Martin Brant; North Arlington, N. J assignors to" Aga Meta-l Tube Company, Elizabeth; Ni J., a corporationor New Jersey Application my 15, 1942,.Serial-No. 443.092

' 3'G1aims. (01-. 153 64) V The present. invention relates: to the manufacture, 0t spiralwound membersand has'particular reference. to the manutacture of; members of tubular formwound. from metal. strip or-skelp to formv a SEIiESgOf. spiral convolutionspwithi the edges of.- adjacent convolutions spaced. apart to provide. ar -continuous open spiral space-or seam usable-as a. threadlike guide tor advancing; axiallyof the member when theinemberuis revolved, a part held against rotation. and; having a. portion engaging thethreadlike; guide.

Spiral wound membersuof. the general character above described have previously been-used as thread members for. advancing .elementstengaging them, but recently: the development-of'new 1 articles of commence. has. created a demand: for

spiral. wound. members a of. the character. under consideration which must meet. more: rigid: specifications-as to dimensions; and spacing thanhas heretofore been. obtainable by the previously 1- .knownmethods for manufacturing; such memhers. I

As an example,- spiral woundmembers-i are; be-

ing. employed .for the purpose. of. raising; and.low-

ering window framesand. the like, andain this use are. required among. other. things to meet relatively. strict specifications aSgtO- both? internal andv external diameter throughout. their: length, uniformity of pitch of the guide. threador space and freedomirombulgin or "curling; of the; wall portionsformedrby the edges of thestripv and defining the walls.- of the thread; guide.

'It is the general object of the-present-invention to provid .an improved methodiior, producing. a spiral. wound member by. spirali wind-ing procedure. which will. enable a member: of-the desiredl'character to be formed which will. be

uniform. within close tolerance limits-at: all-points, with. respect. bothto. internallandv external diamete-r. and which also will. have a uniform pitch of. thread. guide. Other and more-detailed 0b jects. of the inventionand the mannerin which the. several object are. accomplished. may. best be understood from. a consideration of the: en-

suing-portion of this. specificatiomtakeninlconjunction. with the accompanying drawing.- in which;

' Fig. '1.is amore or less:diagr m iv y partly in: sections-of. partroi. a. machine. adapted o p y Wind striphin accordancewith the presentimzention;

.2..is.a view takenpn the..line. 2--2l.of. Fig.1.; T Fig. 3Yis. a. section. of, stripsas ordinarily em.-

ployed heretofore in the prior-art. in. windin members of the kind under consideration; and

comprises asdie. indicated) generally at ll] of and having separable: die bloclt members-10w and. tub held together-by means of bolts IZ'Which: may

heiprovided. with-heavy loading, springs l 4 located under. the; bolt heads [6: in order to permit.- the dierblocks to separate slightly to' avoid break- .ageainicase'of. the; development of. excessive stress. .Eachof. the-die blocks: is'provided' witha semicylindrical: channel which are. 'loca-tedwinz conifnontingrelation toprovide a cylindricalwbore I'll. The stripwlil of the material to be-wound .is fed'tothe. the blocks byknown means. which in the present instance comprises frictionmrollers Ziland 22 engaging the opposite faces; otthe strip.

One or "bothof these-ro-llersmay be -power driven asby; mean pf thepower. shaft 24 andthe necessary friction grip on this strip. obtainedby means of adjustable loadingspringsczfil operating-rte. force the upper r oller 20,.the. axis or whichis movable, toward the fixedlower roller 2 2..

I After passing-; between-the rollers and. before entering thesdiethestrip passesthroug-h aguide channel .28 formed in amemher indicated genorally at 30 which. also carries the feed rollers and which. is: pivotally mounted by means of the pivot bolt --32 to turnabout an axis-atright angles to: theaxis. of v the bore |'l of the die; The member -30 isfclamped'to thelfixed base plate. 3.3. in

desired: adjusted position by means of suitable bolts-and clamping nuts 34 workinginconiunctionwitl the arcuate slotstt-in-member-tfl. Ad- J'ustment of the-position of members!) is effected by means ofthe adjusting; screw- 38': carried by azprojectiom onbase plate 33 and-.lockedin position bymeans of the lock nut 48;

After passing through the guide channel; 28

in. member 30. the strip enters. the bore llof. the

die. tangentially through a suitablechannel-in therdieblockelob and is forced into spiral wound form by the. die. In the. present case th /angle at. whichthe strip is fed, relatiyeto theaxis, of the b.ore..and thewidth of the strip; is'suchthat the. edges. i 2. and 44 of. thestrip, after. the. strip is: wormed-into spiral. convo1utions,- are: spaced apart toiormacontinuous spiral openscamme- .viding athreadlike guidelio.

. Thelgeneral procedure. of winding thusfar described and. commonly known. as air core winding, is not. new and. aspracticed'.heretofore is satisfactory for producing spirahwound members which do not need to coniorm. to strictfldi- .mensional specifications.

.We have discovered, however, that if this procedure. i followed the wound: material,v particularly iii the. metal. is otlferrous .nat'ure suchflas steehwill. tend to produce. .convolutions. which will? spring. .or how. outwardly. immediately.ad. jacent to the edges of the open seam or'thread, giving what may be termed a dished character to the strip transversely thereof. This of course results in non-uniform diameter both internally and externally of the member along its length.

We have further discovered that this defect can largely be overcome by relieving the corners of the edges of the strip which lie on the outside diameter of the member as wound. In Fig. 3 there is shown a strip of the kind ordinarily employed in winding operations of the character under consideration where the member to be produced has an open rather than an overlapped seam. In accordance with the present invention the strip which is wound is relieved at the outer corners of the side edges and this relieving of the corners of the strip may be effected in various specific ways as shown in Fig. 4. For example, the strip l8 may have its outer corners bevelled as shown at Hla. Alternatively these corners may be rounded as shown at [8b. While the inner corners may be permitted to remain sharp it is frequently convenient from the standpoint of strip manufacture to completely round the edges as shown at I80 and we have found that no adverse effect results from modifying the inner corners. The primary requisite appears to be to relieve the outer corners by making them of bevelled, chamfered or rounded form, these various expedients being conveniently referred to generically as relieving the outer corners of the strip.

In addition to the use of strip with relieved outer corners, we have further found that the prevention of dishing of the strip after winding is definitely aided and insured by providing internal support for the strip within the forming die. To this end, we provide a mandrel 48 the shank portion of which has an outer diameter the same as the desired internal diameter of the member to be wound, and the head portion of which bears as at 50 against one end of the die. The mandrel 48 is appropriately centered in the bore I 8 by means of the shouldered head portion 52 and the mandrel is freely rotatable with respect to the die, being turned in the die as the winding operation proceeds, by the friction of the strip against the surface of the mandrel. It will be understood of course that proper lubrication is afiorded for the hearing at the head of the mandrel. It will be apparent that because of the angular direction of the feed of the strip into the bore of the die no means is required other than contact with the strip to prevent the mandrel from backing out of the die.

While the members constituting the final prodduct of the process must conform to close dimensional specifications the uses for such members are such that they must be produced at relatively low cost and for this reason usual commercial grades of strip or skelp must be employed. Such strip or skelp will vary within certain limits as to width and in order to hold the pitch of the thread guide to within required limits of variation, the adjustable head carrying the strip feeding rollers and guide channel is provided. By slightly varying the angle of adjustment of this head, variations in pitch due to variations in width of the strip may readily be com-'- pensated for. Ordinarily the pitch of the finished product will be checked by the machine operator whenever a new roll of strip material is fed into the machine and the feeding head adjusted to secure the proper pitch from the strip of material being used. Thereafter from time to time the pitch is checked and proper adjustment made in the event there should be material variation in width along the length of any given roll of strip material. While automatic mean might be provided for controlling the position of the feeding head under the influence of a pitch gauge constantly engaging the member as it leaves the winding die, we have found that, ordinarily, commercial grades of strip material are sufficiently uniform in widths so that periodic checking of the finished material and manual adjustment of the feeding head if required is sufiicient to. insure adequately accurate pitch.

What is claimed:

1. The method of forming a spiral wound tubular member having a continuous open spiral seam or guide between contiguou convolutions of the member which comprises feeding a strip of sheet metal having a width several timesits thickness and having the outer corners thereof relieved into a suitable rotationally stationary winding die having a bore providing an internal circularly curved forming surface, said feeding being effected at an oblique angle to the axis of the bore appropriate to form a guide space of desired width between adjacent confronting edges of said contiguous convolutions, and supporting the material being wound by a mandrel extending into said bore and freely rotatable with respect to the die under the influence of the friction developed between the mandrel and the material being wound.

2. The method of forming a spiral wound tubular member having a continuous open spiral seam or guide between contiguous convolutions of the member which comprises relieving the outer corners of a strip of sheet metal having a width several times its thickness, feeding the relieved strip so prepared into a suitable rotationally stationary winding die having a bore providing an internal circularly curved forming surface, said feeding 10 being effected at an oblique angle to the axis of terial being wound.

3. The method of forming a spiral wound tubular member having a continuous open spiral seam or guide between contiguous convolutions of the member which comprises feeding a sheet metal strip having a width several times its thickness and having the outer corners thereof relieved into a suitable rotationally stationary winding die having a bore providing an internal circularly curved forming surface, said feeding being effected at an oblique angle to the axis of the bore appropriate to form a guide space of desired width between adjacent confronting edges of said contiguous convolutions, supporting the material being wound by a mandrel extending into said bore and freely rotatable with respect to the die under the influence of the friction developed between the mandrel and the material being wound and varying the angle at which the strip is fed to the die to compensate for variations in thewidth of the strip, whereby to produce uniformity of pitch of said guide space.

WILEY W. McMINN. OLAF MARTIN BRANT. 

